1. Field of the invention
The present invention relates to a method for producing a low bulk density hollow fine powder of alkali metal compound. For example, a low bulk density hollow fine powder of sodium chloride or table salt has expectations as a unique seasoning due to its scarce irritation and improved taste. Special usages are foreseen for low bulk density hollow fine powders of other alkali metal compounds because of their exhibiting peculiar phenomenon in the solubility, reactivity, etc. in comparison with those of coarse powders.
2. Description of the Prior Art
Conventionally, the spray drying method has being employed for producing low bulk density powders. Since the particle size of powder obtained by the method is controlled by the size of fluid sprayed, it has been hard to produce fine powders of micron order size. Mechanical grinding of the spray-dried powder may enable to produce a fine powder, however, the additional one step increases the production cost.